1. Field of the Invention
The present invention relates to a sheet package housing a sheet stack in which a plurality of sheets are stacked, received within a package container having a dispensing opening.
2. Description of the Related Art
Some of sheets for hand cleaning, baby wipes or sheets for cleaning toilet, kitchen and so forth are provided as wet type sheet. Such wet type sheets are sealingly received within a package container, such as a hard packaging vessel and a bag formed of a packaging sheet in order to maintain wet condition. The package container is formed with a dispensing opening so as to permit sequential dispensing of the sheets. On the other hand, this kind of sheets are so combined as to link vertically adjacent sheets with each other, so that next sheet is drawn together with the uppermost sheet to project the upper portion thereof through the dispensing opening when the uppermost sheet is pulled out.
Such type of the sheet package is typically called as pop-up type. Prior art of a sheet stack of the wet type sheet as pop-up type will be discussed with reference to FIGS. 6 and 7.
The sheet stack shown in FIG. 6 is formed by stacking a plurality of folded sheets 80 combined with each other. Each sheet 80 is folded in a folding line 81 to form an upper piece 82 and a lower piece 83. The odd number order sheets 80 and the even number order sheets 80 are combined symmetrically with each other. Between the upper piece 82 and the lower piece 83 of the upper sheet (or the overlying sheet), the upper piece 82 of the lower sheet (or the underlying sheet) is disposed. An overlapping width between the lower piece 83 of the upper sheet and the upper piece 82 of the lower sheet are set in an extent of 30 mm, for example. The lower piece 83 and the upper piece 82 are joined by a water screen.
The sheet stack is housed within a package container 100, such as a hard packaging vessel, a packaging bag or the like, provided with a dispensing opening 100a. Pinching the upper piece 82 of the upper sheet with fingers and pulling out the same through the dispensing opening 100a, the lower sheet is drawn at the upper piece by the lower piece of the upper sheet. Then, due to resistance at the edge portion of the dispensing opening 100a, joining between the upper sheet and the lower sheet by the water screen is broken to separate the upper sheet and the lower sheet. As a result, the upper piece 82 of the lower sheet is projected from the dispensing opening 100a to facilitate dispensing of the next sheet.
Each sheet 90 in the sheet stack shown in FIG. 7 is folded in such a manner that an upper piece 91 is placed at upper side of an intermediate piece 93 and a lower piece 92 is placed at lower side of the intermediate piece 93. Thus, the sheet 90 is folded into substantially Z-shape.
In the sheet stack, the upper piece 91 of the lower sheet is disposed between the intermediate piece 93 and the lower piece 92 of the upper sheet. When the upper piece 91 of the upper sheet is drawn out through the dispensing opening 100a of the package container 100, the upper piece 91 of the lower sheet is trained (or dragged) together with the lower piece 92 of the upper sheet to be drawn out through the dispensing opening 100a to project therefrom.
However, in the sheet stacks shown in FIGS. 6 and 7, the lower sheet is drawn out to project from the dispensing opening 100a when the upper sheet is dispensed through the dispensing opening 100a. For separating the lower sheet from the upper sheet as trained, a resistance force is exerted on the upper piece 82 projecting through the dispensing opening 100a in case of the sheet stack shown in FIG. 6. On the other hand, the resistance force is exerted on the upper piece 91 projecting through the dispensing opening 100a in case of the sheet stack shown in FIG. 7.
Therefore, in the case where strength of each sheet is low in dispensing direction, when the upper piece 82 or 91 projecting from the dispensing opening 100a is drawn out with pinching by fingers, the sheet may be broken at the mid-way of dispensing due to sliding resistance between the edge portion of the dispensing opening 100a and the sheet, or the sheet may be damaged to be locally become thin due to separation between the fibers.
Particularly, when the sheets in the package container 100 is in wet condition, strength of each sheet becomes low. Furthermore, when the sheet 80 or 90 is water-decomposable sheet to be dispersed in large amount of water as disposed into flush toilet after use, the breaking strength in dispensing direction is typically less than or equal to 4.9N per 25 mm width in wet condition. Therefore, the water-decomposable sheet can be damaged by resistance as being dispensed through the dispensing opening 100a. 
For preventing damage to the sheet dispensed as a single sheet as set forth above, an inner width W100 of the dispensing opening 100a is required to be widened to reduce sliding resistance to be exerted on the sheet from the edge portion of the dispensing opening 100a. However, when the inner width W100 of the dispensing opening 100a becomes excessively wide, the sheets within the package container 100 in wet condition can be easily dried. Also, since a cover member closing the dispensing opening 100a becomes excessively large to cause difficulty in certainly adhering the cover member in the circumference of the dispensing opening 100a when the dispensing opening 100a is covered by the cover member. If closure of the dispensing opening 100a by the cover member is incomplete, the sheet can be easily dried.
On the other hand, when number of sheets to be received is smaller as compared with a volume of the package container and when a slight gap is formed between the uppermost sheet and the dispensing opening, resistance to be exerted as dispensing uppermost several sheets becomes smaller. However, in this case, excessive size of the package container becomes necessary as compared with the sheet stack. On the other hand, when the package container is formed with a packaging sheet, the package container is formed by wrapping the sheet stack with the packaging sheet. At this time, it is difficult to continuously and automatically perform operation for packing the sheet stack with maintaining a gap (space) within the package container.
The present invention has been worked out in view of the problems in the prior art as set forth above. It is therefore an object of the present invention to provide a sheet package which can prevent from causing damage to a sheet upon dispensing the sheet through a dispensing opening without widening an opening width of the dispensing opening and providing extra gap within a package container.
According to the first aspect of the present invention, a sheet package includes a sheet stack, in which a plurality of folded sheets are stacked, received within a package container with a dispensing opening,
wherein each individual sheet is folded into two-ply sheet along a first folding line, two sheets of the two-ply sheet are folded along a second folding line extending in parallel to the first folding line together for forming a folded sheet, a plurality of folded sheets are stacked in such a manner that a portion including the first folding line of a lower folded sheet is disposed within a valley folded portion of an upper folded sheet.
The sheet stack may be formed with placing the first folding line of each folded sheet with a width range of the dispensing opening. The sheet may be a water decomposable sheet disposed within the package container in wet condition, the two-ply sheet may have a breaking strength less than or equal to 9.8N per 25 mm width in wet condition in a direction perpendicular to the first folding line. The folded sheets in the sheet stack may include first folded sheets oriented in one direction and second folded sheets oriented in the other direction, the first and second folded sheets may be stacked alternately in such a manner the portion including the first folding line of one of the first and second folded sheet located at lower side may be disposed within the valley folded portion of the other of the first and second folded sheet located at upper side. In the preferred construction, the portion including the first folding line of one of the first and second folded sheets located at lower side and the portion including the first folding line of the other of the first and second folded sheet located at upper side do not overlap with each other on a center line extending in sheet stacking direction. The two-ply sheet may be formed by folding an essentially rectangular flat one-ply sheet at the first folding line inclined to one of opposite shorter edges so that shorter edges of the two-ply sheet as folded along the first folding line are offset from each other, and two sheet fractions continuous across the first folding line for forming the two-ply sheet have mutually different length in a direction perpendicular to a direction along which the first folding line extends, one of the sheet fraction having shorter length of the first and second folded sheets do not overlap with each other as stacked.
According to the second aspect of the present invention, a sheet package comprises:
a package container defining a sheet stack receptacle space and a dispensing opening communicated with the sheet stack receptacle space; and
a sheet stack containing a plurality of sheets, each individual sheets being two-ply sheet consisted of two sheet fractions continuous across a first folding line, a plurality of the two-ply sheets being interfolded with each other in such a manner that when an uppermost sheet is withdrawn through the dispensing opening, a succeeding sheet follows and is separated at the dispensing opening to be retained projecting a portion including the first folding line from the dispensing opening so that portion of the sheet in two-ply structure is constantly gripped as withdrawn from the package container.
According to the third aspect of the present invention, sheet package comprising:
a package container defining a sheet stack receptacle space and a dispensing opening communicated with the sheet stack receptacle space; and
a sheet stack containing a plurality of sheets, each individual sheets being two-ply sheet consisted of two sheet fractions continuous across a first folding line, a plurality of the two-ply sheets being interfolded with each other in such a manner that when an uppermost sheet is withdrawn through the dispensing opening, a succeeding sheet follows and is separated at the dispensing opening to be retained projecting a leading edge including the first folding line from the dispensing opening so that portion of the sheet in two-ply structure is constantly gripped as withdrawn from the package container, the leading edges of vertically adjacent sheets being arranged in non-overlapping manner.
According to the fourth aspect of the present invention, a sheet stack for a sheet package comprises a plurality of sheets, each individual sheets being two-ply sheet consisted of two sheet fractions continuous across a first folding line, a plurality of the two-ply sheets being interfolded with each other in such a manner that vertically adjacent sheets being interlinked at a trailing end portion of an upper sheet and a leading end portion of a lower sheet, so that the lower sheet is placed in a position ready for dispensing after dispensing the upper sheet, and the leading end portion includes a leading edge along which the first folding line extends.
According to the fifth aspect of the present invention, a sheet stack for a sheet package comprises a plurality of sheets, each individual sheets being two-ply sheet consisted of two sheet fractions continuous across a first folding line, a plurality of the two-ply sheets being interfolded with each other in such a manner that vertically adjacent sheets being interlinked at a trailing end portion of an upper sheet and a leading end portion of a lower sheet, so that the lower sheet is placed in a position ready for dispensing after dispensing the upper sheet, and the leading end portion includes a leading edge along which the first folding line extends, and the leading end portions of vertically adjacent sheets being arranged in non-overlapping manner.